Dental materials journal最新文献

The purpose of this study was to develop a new instrument to measure the mechanical properties of rotary endodontic Ni-Ti files (ProTaper Gold F2, ProTaper Ultimate F2, and HyFlex EDM Onefile), and to evaluate the overall utility of the device. The instrument was capable of analyzing the 6-axis force/torque generated by the files during cyclic dynamic movement in a metal curved artificial root canal, and doing automatic cyclic dynamic filing in a resin root canal with a preset vertical force limit by adopting a negative feedback mechanism. By analyzing the 6-axis force/torque, we were able to estimate the position and contact points of the files in the curved root canal. ProTaper Gold showed the highest force/torque in all directions. HyFlex EDM had the highest hysteresis ratio, centering ratio value and NCF (number of cycles to fatigue fracture), while the lowest vertical force.

The study is to evaluate the effects of collagen/hyaluronic acid coating with or without puerarin and exosomes (Exos) derived from adipose stem cells (ADSCs-Exos) on pre-osteoblast proliferation and differentiation on the surface of titanium materials. Titanium materials with different coatings were prepared by layer-by-layer technique, evaluating the surface characterization. Cell functions were assessed by cell biology experiments. Related genes and proteins were assessed by RT-qPCR and Western blot. Puerarin or ADSCs-Exos coating had better effects on promoting the adhesion, proliferation and differentiation of pre-osteoblasts, and the strongest effect was found after their co-coatings, manifesting as the up-regulations of alkaline phosphatase (ALP) activity, collagen type I alpha 1 (Col1a1), runt-related transcription factor 2 (Runx2), osterix and activating transcription factor-2 (ATF-2). Levels of phosphorylated-P38 (p-P38) and p-ATF-2 were up-regulated in pre-osteoblasts grown on puerarin and ADSCs-Exos-loaded titanium surfaces. Titanium surfaces loaded with puerarin and ADSCs-Exos promotes the proliferation and differentiation of pre-osteoblasts.

Currently, dental implants primarily rely on the use of titanium and titanium alloys. However, the extensive utilization of these materials in clinical practice has unveiled various problems including stress shielding, corrosion, allergic reactions, cytotoxicity, and image artifacts. As a result, polyetheretherketone (PEEK) has emerged as a notable alternative due to its favorable mechanical properties, corrosion resistance, wear resistance, biocompatibility, radiation penetrability and MRI compatibility. Meanwhile, the advancement and extensive application of 3D printing technology has expanded the range of medical applications for PEEK, including artificial spines, skulls, ribs, shinbones, hip joints, and temporomandibular joints. In this review, we aim to assess the advantages and disadvantages of PEEK as a dental implant material, summarize the measures taken to address its shortcomings and their effects, and provide insight into the future potential of PEEK in dental implant applications, with the goal of offering guidance and reference for future research endeavors.

Archwire bending is the key to orthodontic treatment, and multi-time bendings are inevitable during manual and robotic automated bending. The purpose of this paper is to quantitatively evaluate the mechanical effects of the different preparation modes and to compare the mechanical properties of the orthodontic loops in one and multiple bends. Three types of typical stainless steel orthodontic loops (vertical loop, T-loop, and L-loop) were used to quantify the mechanical effect of patterns for preparation by experimental comparison between loops with different bending times by using an orthodontic force tester (OFT). The results were statistically analyzed by t-test. The fracture test of the stainless steel archwire was also carried out, and the bending times at fracture were recorded. Results of the tests indicate that one-time and multi-time bending have a significant mechanical effect on orthodontic appliances. Multi-time bending causes significant mechanical decreases and can damage the appliances.

The use of biogenic calcium ions for the source of hydroxyapatite (HAp or HA) are very common and have been being explored extensively. However, it usually results high crystalline HA, due to high reaction and decomposition temperatures. In this study, strontium (Sr²⁺) doped HA from the golden apple snail shells (Pomacea canaliculate L) was successfully synthesized. It was indicated that Sr ions completely replaced calcium (Ca) ions, increased the lattice constant, and consecutively reduced HA crystallinity. Smaller crystal size and β-type carbonate (CO₃^2-) ions substitution with Ca/P close to 1.67 molar ratio that mimic bone crystals were observed in Sr-doped HA, with significant increased rate of MC3T3-E1 cells viability and higher IC₅₀ values. It was proven that Sr ions substitution resolved challenges on the use of biogenic sources for HA fabrication. Further in vivo study is needed to continue to valorise the results into real biomedical and clinical applications.

This project aimed to develop an artificial intelligence program tailored for cephalometric images. The program employs a convolutional neural network with 6 convolutional layers and 2 affine layers. It identifies 18 key points on the skull to compute various angles essential for diagnosis. Utilizing a custom-built desktop computer with a moderately priced graphics processing unit, cephalogram images were resized to 800×800 pixels. Training data comprised 833 images, augmented 100 times; an additional 179 images were used for testing. Due to the complexity of training with full-size images, training was divided into two steps. The first step reduced images to 128×128 pixels, recognizing all 18 points. In the second step, 100×100 pixels blocks were extracted from original images for individual point training. The program then measured six angles, achieving an average error of 3.1 pixels for the 18 points, with SNA and SNB angles showing an average difference of less than 1°.

This study aims to assess the dimensional accuracy of complete denture bases fabricated from different CAD/CAM technologies and a conventional method, including milling (CNC), PolyJet (PJ), laser sintering (SLS), digital light processing (DLP), and injection molding (IM). It also examines the influence of the removal of technology-specific connectors or support structures when present. Denture base surfaces were digitized using a laboratory scanner, and virtual measurement points were calculated with tetrahedral reference geometries. Defined distances were measured in all spatial directions and compared to design data (p<0.05), revealing significant differences in sagittal (p=0.004), transversal (p<0.001), and vertical (p<0.001) dimensions. Connector removal had no significant impact for CNC but significantly affected DLP. All technologies yielded clinically acceptable results, with CNC milling demonstrating the best overall outcome.

Premixed calcium silicate-based materials have recently been developed and are recommended for a wide range of endodontic procedures, including vital pulp therapy. This study investigated the in vitro biocompatibility and pro-mineralization effect and in vivo reparative dentin formation of EndoSequence Root Repair Material, EndoSequence BCRRM, Bio-C Repair, and Well-pulp PT. Both fresh and set extracts had no detrimental effect on the growth of human dental pulp stem cells. The fresh extracts had a higher calcium concentration than the set extracts and induced considerably greater mineralized nodule formation. EndoSequence Root Repair Material had the longest setting time, whereas Bio-C Repair had the shortest. When these materials were applied to exposed rat molar pulps, mineralized tissue deposition was found at the exposure sites after 2 weeks. These results indicate that the premixed calcium silicate-based materials tested could have positive benefits for direct pulp capping procedures.

This study evaluates the 5-year clinical performance of Class II restorations performed with different bulk-fill restorative materials. In the study, Class II restorations performed with Tetric Bulk-Fill (TBF), Filtek Bulk-Fill (FBF), and Equia Forte Fil (EF) were evaluated. One hundred-nineteen restorations were included in the study. Restorations were assessed during the 6th month, 1st, 2nd, and 5th year. Cochran Q, Pearson chi-square, and Fisher-Freeman-Halton tests were used for statistical analysis. In the 5th year, significant differences were observed in terms of retention, color match, marginal adaptation, marginal discoloration, surface texture, and anatomical form in all materials. There was a significant difference between EF and bulk-fill composites only in terms of retention and anatomical form. EF was significantly less successful than bulk-fill composites with regard to retention and anatomical form, but bulk-fill composites have shown similar clinical performance. EF cannot be an alternative to bulk-fill composites for Class II restorations.

This study evaluated fracture resistance of monolithic fixed dental prostheses (FDPs) fabricated using different placement strategies of various connector designs in multilayered zirconia disc. Monolithic FDPs were placed in translucent and dentin layers of multilayered zirconia disc and fabricated with V-shaped and U-shaped connector designs gained by sharp and blunt millings. The FDPs were cemented on abutment models made of polymer material, underwent thermal cycles, and loaded to fracture using the universal testing machine. Fracture loads and modes were analyzed using two-way ANOVA, Tukey's post hoc test, and Fisher exact test (p≤0.05). The chosen placement strategy and connector designs gained by different milling procedures in computer-aided design/computer-aided manufacturing technology affect fracture resistance of monolithic FDPs made of multilayered zirconia materials. Placing the connector in translucent layer rather than dentin layer of multilayered zirconia disc and using sharp milling significantly reduces fracture resistance of monolithic multilayered zirconia FDPs.